• 대한기계학회논문집A
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• 제24권5호
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• pp.1331-1342
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• 2000

In power generation systems a variety of structural components typically operate at high temperature and pressure. Therefore a life assessment methodology accounting for gradual creep fracture is increasingly needed for these components. The most critical defects in such structure are generally found in the form of semi-elliptical surface cracks in the welded tubular joints. Therefore the analysis of a semi-elliptical surface crack in a plate or a shell is an important problem in engineering fracture mechanics. On this background, via shell/line-spring finite element analyses of such surface cracks in the welded T and L joints under various loadings, we investigate J-integral along the crack front We first develop T and L joints auto mesh generation program providing ABAQUS input file composed of shell/line-spring finite elements. We then further develop a T and L joints life assessment program based on the experimental creep crack growth law and auto mesh generation program in a graphical user interface format Finally the remaining life of T and L joints for various analytical parameters are assessed using the developed life assessment program.

• Earthquakes and Structures
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• 제16권5호
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• pp.575-588
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• 2019

Seismic design method based on bearing capacity has been widely adopted in building codes around the world, however, damage and collapse state of structure under strong earthquake can not be reflected accurately. This paper aims to present a deformation-based seismic design method based on the research of RC component deformation index limit, which combines with the feature of Chinese building codes. In the proposed method, building performance is divided into five levels and components are classified into three types according to their importance. Five specific design approaches, namely, "Elastic Design", "Unyielding Design", "Limit Design", "Minimum Section Design" and "Deformation Assessment", are defined and used in different scenarios to prove whether the seismic performance objectives are attained. For the components which exhibit ductile failure, deformation of components under strong earthquake are obtained quantitatively in order to identify the damage state of the components. For the components which present brittle shear failure, their performance is guaranteed by bearing capacity. As a case study, seismic design of an extremely irregular twin-tower high rise building was carried out according to the proposed method. The results evidenced that the damage and anti-collapse ability of structure were estimated and controlled by both deformation and bearing capacity.

• 한국압력기기공학회 논문집
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• 제12권1호
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• pp.30-40
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• 2016

The paper investigates the previous studies about welding residual stresses in nuclear components. First, various residual stress measurement methods are reviewed in applicability. Second a finite element welding residual stress analysis technique, which was developed from the viewpoint of FFS (Fitness-For-Service) assessment, is explained. Third, characteristics of the welding residual stresses on J-groove welds and butt welds were presented via investigating the previous studies. Last, engineering formulae for residual stresses in the FFS assessment codes such as R6 and API 579/ASME FFS-1 Code is summarized.

• 환경영향평가
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• 제15권1호
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• pp.45-52
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• 2006

The purpose of this study is to assess spatiotemporal variation of coastal water quality according to time and location changes. For this we developed numerical marine trophic index base on four water quality components (chlorophyll, suspended solids, dissolved inorganic nitrogen and phosphorus) and applied this index to the water quality data measured in the korean coastal zone for the 7-years period from 1997 to 2003. Water quality data are obtained only at selected sites even though they are potentially available at any location. Therefore, in order to estimate spatial variation of coastal water quality, it is necessary to estimate the unknown values at unsampled locations based on observation data. In this study, we used IDW (Inverse Distance Weighted) method to predict water quality components at unmeasured locations and applied marine trophic index to predicted values obtained by IDW interpolation. The results of this study indicate that marine trophic index and spatial interpolation are useful for understanding spatiotemporal characteristics of coastal water quality.

• 대한조선학회논문집
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• 제34권2호
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• pp.75-84
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• 1997

본 연구에서는 스펙트럼 해석법에 기초한 새로운 개념의 정밀한 선체구조 피로강도평가 시스템을 개발하였으며 membrane 방식 LNG 운반선을 대상으로 하여 수치계산을 수행함으로써 그 효용성을 검증하였다. 선체에 작용하는 파랑하중을 스트립 이론으로 직접계산하고 3차원 정밀 구조해석과 영향계수 개념을 바탕으로 Miner 법칙에 의한 누적손상도를 계산하여 설계기준과 비교, 검토하였다.

• 한국기후변화학회지
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• 제8권4호
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• pp.339-346
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• 2017

The Korea Adaptation Center for Climate Change (KACCC) located in Korea Environment Institute has serviced a climate change vulnerability assessment support tool (VESTAP) since 2014 in order to help local governments to establish their own adaptation plans. Owing to its easy usage, the VESTAP has been utilized by not only local governments but also academia for examination of climate change vulnerability in various fields. However, the KACCC has not suggested a standard usage how to compose indices for climate exposure, sensitivity, and adaptation capacity which are main components of vulnerability although the KACCC manages operation and application of the VESTAP. Many users had no choice but to compose indices based on their own interpretation on the components of vulnerability. This technical note suggests the standard usage of VESTAP by reevaluating some vulnerability assessments previously developed. This may help users to correctly compose indices for climate change vulnerability assessment, and may minimize possibility of inter-user inconsistency in definition of vulnerability assessments.

• 한국신뢰성학회지:신뢰성응용연구
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• 제9권3호
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• pp.219-231
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• 2009

Power light emitting diodes(LED) for lighting fittings are so much environment-friendly, highly reliable and consume less energy that they are widely used at home and in industries such as electronics, telecommunications and industrial machineries. However, they are exposed to a very diverse environment and consists of complex components and, therefore needs careful approach to the enhancement and assessment of reliability of the item. In this article reliability assessment criteria for LED are established in terms of performance assessment test, reliability assessment test and accelerated test.

• Bulletin of the Korean Chemical Society
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• 제34권3호
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• pp.863-867
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• 2013

A series of azo disperse dyes having dicyanovinyl groups was synthesized by the Knoevenagel condensation with malononitrile from carbonyl substituted phenylazo disperse dyes which were prepared by conventional diazo coupling reaction of aniline derivatives as diazo components. A variety of coupling components such as anilines, an indole and a pyridone were used. The azo disperse dyes were evaluated for their spectral properties and dyeing assessment on the polyester fabrics. The azo disperse dyes containing dicyanovinyl groups showed bathochromic shifts and darker colors due to increased electron withdrawing strength in their azo components and extended conjugation by dicyanovinyl groups than their parent carbonyl substituted azo dyes. The dyes containing 2-acetylamino-5-methoxy substituent in the coupling component exhibited higher wavelength of maximum absorbance (${\lambda}_{max}$) and significant negative solvatochromism than those of other dyes due to intramolecular hydrogen bonding.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.914-919
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• 2000

In most case high temperature components in fossil power plant are damaged by fatigue, creep and degradation. Design of power plant components is based on ideal loading such as temperature, pressure and so on. But in many cases unexpected loadings are applied at components. A key ingredient in plant life extension is the preventive diagnosis technology and remaining-life-assessment technology. This paper describes diagnosis technology and life-assessment technology for power plant boiler. It helps in setting up proper inspection schedules, maintenance procedures, and operating procedure.

• 한국초등과학교육학회지:초등과학교육
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• 제42권1호
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• pp.47-63
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• 2023

이 연구에서는 2015 개정 교육과정에 따른 초등학교 과학과 검정 교사용 지도서의 3~4학년 물질 영역에 나타난 PCK 요소를 분석하였다. 2009 개정 교육과정에 따른 중학교 교사용 지도서와 달리 상대적으로 PCK 요소의 편차가 작았다. 평균적으로 과학 내용에 관한 지식이 가장 높은 비율을 차지하였고, 과학 교수 전략에 관한 지식이 과학 교육과정에 관한 지식보다 비율이 높게 다뤄졌다. 과학 평가에 관한 지식은 출판사 간 편차가 가장 컸으며, 학생에 관한 지식은 대부분의 출판사에서 비율이 낮게 나타났다. 하위요소로는 개념 및 이론보다 실험 및 탐구의 비율이 높았다. 수직 연계와 수업 목표에 비해 수평연계의 비율이 낮았고, 수업 목표는 교과 역량, 성취기준 등으로 다양하게 제시되었다. 발문이 강조됨에 따라 지도 전략과 발문이 비슷한 비율로 나타났다. 동기 및 흥미, 오개념은 지도 전략, 발문과의 연계가 나타났다. 평가 문항과 평가 준거는 수준별로 제시된 경우가 있었으며, 이 두 요소를 중심으로 다양한 PCK 요소의 연계가 있었다. 출판사별 편차가 상대적으로 큰 요소는 보충·심화 개념, 교과서 탐구, 활동 순서 및 방식, 교과 특이적 전략, 평가 문항이었다. 이상의 연구 결과를 중심으로 추후 교사용 지도서 개발을 위한 시사점을 논의하였다.